From b8596dca9bef5ba7a2d849174e178e7ef3edf46d Mon Sep 17 00:00:00 2001 From: thuanquang Date: Wed, 21 Oct 2026 18:41:59 +0700 Subject: [PATCH] docs(shader): say that S#s without a mip filter also read a multi-level view at its base Co-Authored-By: Claude --- docs/dev/debt/shader.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/docs/dev/debt/shader.md b/docs/dev/debt/shader.md index ecbd7d850e..b38c7e0d0e 100644 --- a/docs/dev/debt/shader.md +++ b/docs/dev/debt/shader.md @@ -60,7 +60,7 @@ - [3D image accesses bound to a 2D or 2D-array T#](../../../core/shader/recompiler/Optimization/src/ResourceMaterializer.cpp) follow CouchRiv's [hardware oracle](../HW_ORACLE.md) measurement on RDNA2 (gfx1036, #2023) and adriadam10's (gfx1035, #2140), not the PS5's gfx1013. On a 2D T#, `image_sample_lz` ignores r and reads the (u,v) texel, `image_load` and `image_load_mip` read the (x,y) texel when z is 0 and return zero otherwise, and `image_get_resinfo` returns (width, height, 1, levels). On a 2D-array T#, these accesses behave like dim 2D-array: r or z is the layer, and `image_get_resinfo` returns the layer count as its third component. Every other access of such an image, including samples with an LOD, bias, derivatives, offset or comparison, gathers, `image_get_lod` and stores, keeps throwing because it is not measured. - [2D-array samples through a 3D T#](../../../core/shader/recompiler/Optimization/src/ResourceMaterializer.cpp) (`image_sample`, `image_sample_l` and `image_sample_lz` with DIM 2D_ARRAY) sample the volume as DIM 3D does: the third address VGPR is the normalized r coordinate, addressed by the sampler's Z mode (only wrap was measured), not a layer index, and a plain sample in a pixel shader takes its LOD from the derivatives of all three coordinates. Measured on RDNA2 (RX 6700 XT, gfx1031, driver 32.0.21045.5002, Windows 11) with the [hardware oracle](../HW_ORACLE.md) template run through the driver's comgr and HIP runtime, not on the PS5's gfx1013: on 16x16x4 R32_FLOAT 3D T#s with one and three levels, the three instructions with DIM 2D_ARRAY returned the same value as with DIM 3D in all 256 lanes of 66 cases (point, bilinear and z-linear filters, wrap addressing, r from -0.125 to 3, quad steps of 1 to 4 texels in u and v and of 0 to 4 slices in r, LOD 1). Other samples of such a pair (bias, LOD clamp, derivatives, offsets, comparison, 16-bit addresses), gathers, `image_get_lod` and a sample mixed with a load of the same image keep throwing because they are not measured. The host sampler ignores `Z_FILTER`, as for every 3D sample, so r is filtered with the XY filter. - [2D accesses through a cube T#](../../../core/shader/recompiler/Optimization/src/ResourceMaterializer.cpp) (#4139) read the T#'s `BASE_ARRAY` face as a cube access with face coordinate 0 does, measured on RDNA1 (gfx1010, RX 5700 XT) with the [hardware oracle](../HW_ORACLE.md) template run through the Windows driver's comgr and HIP runtime on 8x8 and 32x32 32_FLOAT cubes (`DEPTH` 5 and 11, `BASE_ARRAY` 0 and 6): `image_sample_lz`, plain `image_sample` (one level, and six levels in 2x2 compute quads) and `image_sample_l` (the third address VGPR is the LOD, integer and fractional) with DIM 2D equal DIM CUBE with face 0 on every row, with point and bilinear filters, wrap, clamp and mirror addressing and `DISABLE_CUBE_WRAP` 0 and 1, and the VGPR after the two coordinates is not read; `image_load` with DIM 2D reads texel (x, y) of the `BASE_ARRAY` face. So the face coordinates are cube coordinates in [1, 2]: the texel is `floor((u - 1) * width)`. They are translated through the cube mode DIM CUBE accesses use, which samples the face of the 2D-array view at (u - 1, v - 1) with the S# addressing. That matches the hardware inside the face, except within half a texel of its edges with a bilinear filter and `DISABLE_CUBE_WRAP` 0, where the hardware blends texels of the neighbouring faces (also measured on RDNA2, gfx1035, 8x8 cubes with `BASE_ARRAY` 0 and 6). Outside it the hardware clamps a coordinate below 1 to the first texel under every filter, wrap mode and `DISABLE_CUBE_WRAP` setting measured, clamps a coordinate of 2 or more to the last texel when `DISABLE_CUBE_WRAP` is 0 (point filter) and applies the S# addressing to it when it is 1; the translation does none of this, as for DIM CUBE. Only `image_sample_lz`, plain `image_sample`, `image_sample_l`, mip-less `image_load`, and mip-less `image_store` to an image the program only stores to take this mode. Such a store writes texel (x, y) of the `BASE_ARRAY` face, measured on RDNA2 (gfx1036, [by simonbbby](https://github.com/boykopovar/AnyPS5/pull/6799#issuecomment-6217609589), not the PS5's gfx1013) with the [hardware oracle](../HW_ORACLE.md) on 8x8 mip-less cube arrays (`DEPTH` 11) of 32_UINT, 32_FLOAT and 16_16_16_16_FLOAT ([the last also by simonbbby](https://github.com/boykopovar/AnyPS5/pull/6799#issuecomment-6224023050), with exactly representable half values) with `BASE_ARRAY` 0 and 6, wave32 and wave64: the 64 stored texels land on that face and every other byte of the 64 KiB backing is unchanged. Other formats, and Crimson Desert's own 256x256 tiled descriptor, are not measured. Other DIM 2D accesses through a cube T# (gathers, bias, comparison, offsets, derivatives, atomics, stores to an image the program also reads, stores of formats written through a conversion such as 32_SINT, mip loads and stores) still throw. -- [Unnormalized S#s](../../../core/shader/recompiler/Optimization/src/DescriptorBindingBuilder.cpp) are accepted only when direct and used only by `image_sample` without comparison or `_a`, on a single-layer 1D or 2D view that is one level at mip 0 or is read only by `image_sample_lz`, even when the image is also sampled through a normalized S#. +- [Unnormalized S#s](../../../core/shader/recompiler/Optimization/src/DescriptorBindingBuilder.cpp) are accepted only when direct and used only by `image_sample` without comparison or `_a`, on a single-layer 1D or 2D view that is one level at mip 0 (even when the image is also sampled through a normalized S#), or that only unnormalized S#s sample, each without a mip filter or only by `image_sample_lz` without minimum LOD or bias. - [Unnormalized texel offsets](../../../core/shader/recompiler/SpirvBackend/src/SpirvImageEmitter.cpp) are added to the f32 coordinates: exact on RDNA2 (gfx1035), which applies the offset before the clamp ([measured by adriadam10](https://github.com/boykopovar/AnyPS5/pull/822#issuecomment-6033192725)). - [Cube image gradients](../../../core/shader/recompiler/SpirvBackend/src/SpirvImageEmitter.cpp) (shader recompiler) - `image_sample_d` and `image_sample_cd` on a cube pass their gradients to the host sample without the -1.0 that moves the face coordinates from [1, 2] to [0, 1], as Mesa's AMD lowering builds them (`src/amd/common/nir/ac_nir_lower_tex_coords.c`, `prepare_cube_coords`: face-space derivatives with no offset, coordinates offset by 1.5). Measured on RDNA2 (gfx1035) with the [hardware oracle](../HW_ORACLE.md): on a 16x16 32_FLOAT cube with five levels, point mip filter, `image_sample_d` reads the level of `round(log2(16 * max(|ddx|, |ddy|)))` for gradients of 2^(level ± 0.3) texels on each of the four components, both signs, mixed components, every face and two coordinates (1032 rows). `image_sample_cd` takes one level per quad of lanes, from the gradients of its first lane; the host sample computes it per lane. - [Image atomics](../../../core/shader/recompiler/Optimization/src/ResourceMaterializer.cpp) on 32_SINT and 32_FLOAT surfaces act on the raw dword through an R32_UINT storage view. On gfx1100 (RDNA3, [hardware oracle](../HW_ORACLE.md), wave32 and wave64), all 13 integer image atomics, `swap` to `dec`, return the old dword and store the raw-dword result identically on 32_UINT, 32_SINT and 32_FLOAT T#s, over 121 old/data pairs per op, among them 0x80000000, 0xffffffff, 1.0, -1.0 and NaN: `add` adds the bits and `umin` is unsigned on every format. A 16_UINT control differs, so the format is read. gfx1031 (RDNA2) gives the same rows, and its `fmin`, `fmax` and `fcmpswap`, which gfx1100 lacks, also match on the three formats ([measured by thuanquang](https://github.com/boykopovar/AnyPS5/pull/7939#issuecomment-6275099482)). The console's gfx1013 is unmeasured. Other formats throw.